Accepted just means that the IRS has it.
The IRS says most refunds will be issued within 21 days - some faster, some longer.
Each tax return is evaluated on it's own merits. There is no first-in-first-out. Two similar tax return submitted at the same time can have totally different processing times based on IRS criteria for examining tax returns that the IRS does not divulge.
Some returns will be held for ID verification or other verification. The IRS will send a letter if they require more information to process your tax return.
The 2015 PATH ACT passed by Congress mandated that tax refunds be held if the tax return claimed the Earned Income Credit or Additional Child Tax Credit in order to allow the IRS time to match wage statements (W-2's and 1099's) against the claimed income to combat fraudulent tax returns claiming income that did not exist and receive refunds before the IRS could process the wage statements.
Beginning in 2016, if you claim the EITC or ACTC on your tax return, the IRS must hold your refund until mid February This new law (PATH Act) requires the IRS to hold the entire refund.
Those refunds are usually released late February.
Check your refund stratus here:
Check your state refund here: